/* 标准盒子模型 */
.box{
    width: 150px;
    height: 100px;
    padding: 25px;
    border: 5px solid blue;
    margin: 10px;
}

/* 替代盒子模型 */
.alternate{
    box-sizing: border-box;
    border-color: red;
}

/* 外边距 */
.container{
    width: 300px;
    height: 200px;
}

.row{
    box-sizing: border-box;
    height: 33.3%;
    width: 100px;
    border: 1px solid blue;
    /* margin: -32px; */
    /* margin-top: 5px; */
    /* margin-right: 5px; */
    /* margin-bottom: 5px; */
    /* margin-left: 5px; */
    /* margin: 1px 2px 3px 4px; */
}

/* 水平居中 */
.row_center{
    margin: 0 auto;
}

/* 边框 */
.input_username{
    border: none;
    outline: none;
    /* border-top:none;
    border-left: none;
    border-right: none; */
    border-bottom: 5px double blue ;
}

.input_username:focus{
    /* border-bottom: 5px double green ; */
    border: 5px double green ;
    border-radius: 20px;
}

.container2{
    box-sizing: border-box;
    width: 100px;
    border: solid 10px red;
    padding-left: 100%;
}

.menu li{
    display: inline-block;
    width:100px;
    border: 1px solid blue;
    margin-left: 10px;;
    border-radius: 5px;
}

.menu li:hover{
    border-color: red;
    cursor: pointer;
}



